Intravalvular oyster fluid as a innovation matrix for quantification of nitrite

Geane Castro; Sildiane Martins Cantanhêde; Elaine Nunes Teixeira; Lina Clara Moreno; Isabel Vitória Figueiredo; Raimunda Fortes Carvalho-Neta; Ligia Tchaicka; Sandra Fernanda Loureiro de Castro Nunes

doi:10.1590/SciELOPreprints.15698

##article.authors##

Geane Castro State University of Maranhão https://orcid.org/0000-0002-6700-9013
- Writing – Original Draft Preparation
- Conceptualization
- Methodology
- Data Curation
Sildiane Martins Cantanhêde Federal University of Para https://orcid.org/0000-0001-9327-1341
- Data Curation
- Formal Analysis
- Writing – Original Draft Preparation
Elaine Nunes Teixeira State University of Maranhão https://orcid.org/0000-0003-3188-2694
- Writing – Original Draft Preparation
- Data Curation
- Investigation
Lina Clara Moreno State University of Maranhão https://orcid.org/0000-0001-7244-7977
- Data Curation
- Writing – Original Draft Preparation
- Validation
Isabel Vitória Figueiredo University of Coimbra https://orcid.org/0000-0003-0127-4575
- Validation
- Writing – Review & Editing
Raimunda Fortes Carvalho-Neta State University of Maranhão https://orcid.org/0000-0002-3519-5237
- Writing – Original Draft Preparation
- Validation
Ligia Tchaicka State University of Maranhão https://orcid.org/0000-0003-1993-1377
- Writing – Original Draft Preparation
- Validation
Sandra Fernanda Loureiro de Castro Nunes State University of Maranhão https://orcid.org/0000-0002-8358-7606
- Supervision
- Project Administration
- Writing – Review & Editing

DOI:

https://doi.org/10.1590/SciELOPreprints.15698

Keywords:

Biomonitoring, bivalve, aquatic toxicity

Abstract

Among the organisms used as biomonitors, oysters stand out due to the large amounts of contaminants that accumulate in their tissues. The objective of this research was to determine the physicochemical parameters of the estuarine system at three points in São José Bay, Maranhão - Brazil, to perform the biometry of oysters, and to quantify nitrites (NO₂^-) in the intravalvular fluid of oysters. The physicochemical parameters of the brackish water showed that dissolved oxygen presented values below the levels recommended by Brazilian legislation. The pH and temperature remained within the established limits. In the biometric analysis, it was possible to observe that the oysters from harvesting areas are smaller in all dimensions, especially during the rainy season. The result of the quantification of NO₂^- in the oyster supernatant revealed significantly higher concentrations in the harvesting area, showing that this area is the most impacted when compared to the urban area and farm area (control group). The results indicate that the quantification of NO₂⁻by the modified Griess reaction is a valid, simple, effective and low-cost method that can be used in environmental monitoring, in addition to the physicochemical parameters of the water and oyster biometric analysis. The use of oyster supernatant for NO₂^- quantification proved to be a new sampling unit that is easy to collect. The present study may help in biomonitoring studies through the quantification of NO₂^- in the oysters’ supernatant.